06/10/2026
LIGHT STEEL FRAME CONSTRUCTION – PART 2
FASTENING THE FRAME – WHY THE RIGHT SCREW MATTERS
In Part 1 of our Light Steel Frame series, we looked at LSF construction and the growing role it plays in modern building.
Now we move to the steel skeleton itself.
Before insulation, cladding or plasterboard can be fitted, the LSF frame first has to be assembled. And although the screws used to connect that frame may be among the smallest components in the entire building, choosing the correct fastener matters.
The correct screw is not simply one that can drill through the steel. It must make the correct connection.
THE DRILL POINT – BIGGER IS NOT ALWAYS BETTER
Self-drilling screws are available with different drill points, designed for different material thicknesses and applications.
No. 1 Drill Point
Designed for stitching thin-gauge material, including flashing and sheeting at end and side laps, as well as fixing into thin-gauge metal battens.
No. 2 Drill Point
Drilling capacity of approximately 2.5 mm in cold-rolled steel.
No. 3 Drill Point
Drilling capacity of approximately 4.5 mm. This is a commonly used drill point for applications such as fixing sheeting to cold-rolled lipped channel.
No. 5 Drill Point
Drilling capacity of approximately 12.5 mm and used for heavier hot-rolled steel sections.
Looking at those figures, it might seem logical to assume that a No. 3 drill point must be “better” than a No. 1.
Not when fastening thin-gauge LSF steel.
A drill point designed for substantially thicker steel can remove or distort more material than necessary. If the resulting hole is too large, there may be insufficient steel for the screw thread to engage effectively.
More drilling capacity does not mean a better connection. The drill point must suit the material being fastened.
MAIN FRAME CONNECTIONS AND TRUSS POINTS
One of the screws used for main LSF frame connections and truss points is the:
#14 × 22 mm Stitching Wafer – No. 1 Drill Point
There is more engineering in this little screw than its size might suggest.
The #14 Stitching Wafer has a tapered shaft and coarse thread designed to pull two layers of thin sheet steel tightly together as the screw is driven home.
The No. 1 drill point is suited to the thin-gauge material, while the coarse thread engages with the steel and helps draw the two members firmly together.
For lighter or general frame connections, #10 or #12 × 16 mm Wafer screws with a No. 1 drill point are also used, depending on the connection requirement.
WHY A WAFER HEAD?
Take a close look at the photograph accompanying this article.
The fixing position in the LSF member has been formed with a recess or indent.
The broad, low-profile wafer head seats neatly into this recessed area, allowing the completed connection to remain as flush as possible with the face of the steel frame.
Why does that matter?
Because cladding or lining material still has to be installed over the frame. A screw head protruding from the steel can interfere with the board sitting flat against the framing.
The wafer head therefore isn't simply a different style of screw head. Its low profile serves a practical purpose in the completed LSF system.
STUD-TO-TRACK CONNECTIONS
Another wafer-head fastener used in LSF construction is the:
#10 × 22 mm Wafer – Class 3
This screw is used for joining studs and tracks, including connections at pre-punched fixing holes where plasterboard will subsequently be fitted.
Again, the wafer head provides the low-profile connection required so that the next layer of material can sit correctly against the frame.
SMALL SCREW. IMPORTANT JOB.
There is a useful lesson in something as seemingly simple as an LSF frame screw.
The drill point must suit the thickness of the steel.
The thread must achieve effective engagement.
The screw size must suit the connection.
The head design must suit what happens next in the construction process.
And corrosion protection must also be appropriate for the environment in which the fastener will be used.
So when selecting a fastener for Light Steel Frame construction, the question shouldn't simply be:
“Will this screw drill through the steel?”
A better question is:
“Is this the correct screw for this connection?”
That small distinction can make a very big difference.
Next in our LSF series: another small fastener with a very specific job.
